[Greg Locock]

Eeyore wrote in
:



Greg Locock wrote:

Eeyore wrote

No. It won't work. You can only ever meaningfully cancel sound over
a tiny area (volume).

Such as the entire cabin of a passenger aircraft, or in some
circumstances even a car park or a harbour- if you can superimpose
the correcting source and he original.

'tiny' beng a somewhat loose term.

You can't do either of the above. Simply because the noise signal is
quite different for every part of those spaces. It is NOT one simple
signal, it's massively complex.




Since it has been demonstrated, documented, and done, I fail to see your
problem.

One of the very early demonstrations of active noise cancellation used a
single source cancelling a ship's exhaust noise.

I have instaled mics on the outside of a car, and demonstrated
cancellation of exhaust noise. Not a generally useul technique, but it
worked.

Finally, anc was used to cancel prop noise inside an aircraft's cabin.

So, what's your problem?


Cheers

Greg Locock